Feeder cable reduction

ABSTRACT

The present disclosure allows transmission of multiple signals between masthead electronics and base housing electronics in a base station environment. At least some of the received signals from the multiple antennas are translated to being centered about different center frequencies, such that the translated signals may be combined into a composite signal including each of the received signals. The composite signal is then sent over a single feeder cable to base housing electronics, wherein the received signals are separated and processed by transceiver circuitry. Prior to being provided to the transceiver circuitry, those signals that were translated from being centered about one frequency to another may be retranslated to being centered about the original center frequency.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.12/768,515, filed Apr. 27, 2010, which was a continuation of U.S. Pat.No. 7,729,726, issued on Jun. 1, 2010, the disclosures of bothapplications are hereby incorporated by reference in its entirety;therefore, the present application claims priority to both theapplication and patent.

FIELD OF THE INVENTION

The present invention relates to radio frequency communications, and inparticular to translating signals received at one frequency frommultiple antennas to being centered about different frequencies, andcombining these signals for delivery over a common antenna feeder cable.

BACKGROUND OF THE INVENTION

In cellular communication environments, the electronics used tofacilitate receiving and transmitting signals is distributed between abase housing and a masthead, which is mounted atop a building, tower, orlike mast structure. The actual antennas used for transmitting andreceiving signals are associated with the masthead. The masthead willgenerally include basic electronics to couple the antennas tocorresponding antenna feeder cables, which connect to transceiver andamplifier electronics located in the base housing.

Historically, the amount of electronics placed in the masthead has beenminimized, due to inhospitable environmental conditions, such aslightning, wind, precipitation, and temperature extremes, along with thedifficulty in replacing the electronics when failures occur. Maintenanceof the masthead is time-consuming and dangerous, given the location ofthe masthead. Minimizing the electronics in the masthead has resulted inessentially each antenna being associated with a separate antenna feedercable.

As time progressed, the cost of the electronics has been greatlyreduced, whereas the cost of the antenna feeder cables has heldrelatively constant, if not increased. Thus, a decade ago the antennafeeder cables were an insignificant cost associated with a base stationenvironment, whereas today the cost of the antenna feeder cables is asignificant portion of the cost associated with the base stationenvironment. Accordingly, there is a need to minimize the number ofantenna feeder cables associated with a base station environment,without impacting the functionality or operability of the base stationenvironment. Further, there is a need to minimize the increase in costassociated with the masthead and base housing electronics due tominimizing the number of antenna feeder cables required to connect themasthead electronics to the base housing electronics.

SUMMARY OF THE INVENTION

The present invention allows transmission of multiple signals betweenmasthead electronics and base housing electronics in a base stationenvironment. At least some of the received signals from the multipleantennas are translated to being centered about different centerfrequencies, such that the translated signals may be combined into acomposite signal including each of the received signals. The compositesignal is then sent over a single feeder cable to base housingelectronics, wherein the received signals are separated and processed bytransceiver circuitry. Prior to being provided to the transceivercircuitry, those signals that were translated from being centered aboutone frequency to another may be retranslated to being centered about theoriginal center frequency. In one embodiment, the multiple antennasrepresent main and diversity antennas. In such an embodiment, thereceived signals from the diversity antenna(s) may be translated andcombined with the signal received from the main antenna. The receivesignal from the main antenna may or may not be translated prior tocombining with the translated signals from the diversity antenna(s). Thepresent invention is applicable in single mode and multi-modeenvironments. It is also applicable to systems which use four branchreceive diversity. Future systems such as MIMO which may use twotransmit signals and four receive signals per sector will also greatlybenefit from this invention. In essence this invention can be leveragedin any deployment scenario where there are more receive signals thantransmit signals.

Those skilled in the art will appreciate the scope of the presentinvention and realize additional aspects thereof after reading thefollowing detailed description of the preferred embodiments inassociation with the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawing figures incorporated in and forming a part ofthis specification illustrate several aspects of the invention, andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a block representation of a base station environment accordingto one embodiment of the present invention.

FIG. 2 is a block representation of base housing electronics andmasthead electronics according to a first embodiment of the presentinvention.

FIG. 3 is a graphical illustration of a frequency translation processaccording to the embodiment of FIG. 2.

FIG. 4 is a block representation of base housing electronics andmasthead electronics according to a second embodiment of the presentinvention.

FIG. 5 is a graphical illustration of a frequency translation processaccording to the embodiment of FIG. 4.

FIG. 6 is a block representation of base housing electronics andmasthead electronics according to a third embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments set forth below represent the necessary information toenable those skilled in the art to practice the invention and illustratethe best mode of practicing the invention. Upon reading the followingdescription in light of the accompanying drawing figures, those skilledin the art will understand the concepts of the invention and willrecognize applications of these concepts not particularly addressedherein. It should be understood that these concepts and applicationsfall within the scope of the disclosure and the accompanying claims.

The present invention facilitates the reduction of cabling required in abase station environment. In general, signals that were normallytransmitted over separate cables are frequency shifted about differentcenter frequencies, combined, and sent over a single cable. At areceiving end of the cable, the combined signals are recovered andprocessed in traditional fashion. The invention is particularly usefulin a diversity environment, wherein multiple antennas are used toreceive a common signal. In such an environment, certain of the signalsreceived from the main and diversity antennas are shifted in frequency,combined with one another, and transmitted over a common cable.Accordingly, each sector, which includes a main and one or morediversity antennas, will need only one cable for transmitting thereceived signals from the antennas to electronics in a base housing.

Prior to delving into the details of the present invention, an overviewof a base station environment 10 is illustrated in FIG. 1 according toone embodiment of the present invention. The illustrated base stationenvironment 10 is exemplary of the primary components in a cellularaccess network. A base housing 12 is provided in a secure location inassociation with a mast 14, which may be a tower or other structure nearthe top of which is mounted a masthead 16. Communications for the basestation environment 10 are distributed between the masthead 16 and thebase housing 12. In particular, the base housing 12 will include basehousing electronics 18, which include the primary transceiver and poweramplification circuitry required for cellular communications. Themasthead 16 will include masthead electronics 20, which generallycomprise the limited amount of electronics necessary to operativelyconnect with multiple antennas 22, which are mounted on the masthead 16.The masthead electronics 20 and the base housing electronics 18 arecoupled together with one or more feeder cables 24. For the illustratedembodiment, there are six antennas 22 divided into three sectors havingtwo antennas 22 each. For each sector, one feeder cable 24 is providedbetween the masthead electronics 20 and the base housing electronics 18.Accordingly, there are three feeder cables 24 illustrated in FIG. 1. Intraditional base station environments 10, each antenna would beassociated with one feeder cable 24.

Turning now to FIG. 2, a block representation of the base housingelectronics 18 and one sector of the masthead electronics 20 is providedaccording to one embodiment of the present invention. Notably, there aretwo antennas 22 illustrated. A first antenna is referred to as a mainantenna 22M, and the second antennas is referred to as a diversityantenna 22D. For signals transmitted from the main antenna 22M, a signalto be transmitted will be provided over the feeder cable 24 to aduplexer 26 in the masthead electronics 20. The signal to be transmitted(MAIN TX) is sent to another duplexer 28 and transmitted via the mainantenna 22M.

For receiving, signals transmitted from remote devices will be receivedat both the main antenna 22M and the diversity antenna 22D. The signalsreceived at the main antenna 22M are referred to as the main receivesignals (MAIN RX), and the signals received at the diversity antenna 22Dare referred to as the diversity receive signals (DIVERSITY RX). Inoperation, the main receive signal received at the main antenna 22M isrouted by the duplexer 28 to a low noise amplifier (LNA) 30, which willamplify the main receive signal and present it to main frequencytranslation circuitry 32. The main frequency translation circuitry 32will effect a frequency translation, which is essentially a shift of themain receive signal from being centered about a first center frequencyto being centered around a second center frequency. The main frequencytranslation circuitry 32 may take the form of a mixer, serrodyne, or thelike, which is capable of shifting the center frequency of the mainreceive signal.

Similarly, the diversity receive signal received at the diversityantenna 22D may be filtered via a filter 34 and amplified using an LNA36 before being presented to diversity frequency translation circuitry38. The diversity frequency translation circuitry 38 will effect afrequency translation of the diversity receive signal from beingcentered about the first center frequency to being centered about athird center frequency. Preferably, the first, second, and third centerfrequencies are sufficiently different as to allow signals beingtransmitted or received at those frequencies to be combined withoutinterfering with one another.

With reference to FIG. 3, a graphical illustration of the frequencytranslation process is provided. As illustrated, the main and diversityreceive signals are centered about the first center frequency f_(C1),wherein the translated main receive signal is centered about centerfrequency f_(C2) and the translated diversity receive signal is centeredabout center frequency f_(C3). The center frequencies are sufficientlyspaced along the frequency continuum to avoid any interference betweenthe signals transmitted on those center frequencies.

Returning to FIG. 2, the translated main receive signal and thetranslated diversity receive signal provided by the main and diversityfrequency translation circuitries 32 and 38 are then combined withcombining circuitry 40 and presented to the duplexer 26. The duplexer 26will then transmit the composite signal to the base housing electronics18.

The composite signal will be received by a duplexer 40 and provided toseparation circuitry 42, which will effectively separate the translatedmain receive signal and the translated diversity receive signal andprovide them to main frequency translation circuitry 44 and diversityfrequency translation circuitry 46, respectively. The translated mainand diversity receive signals will be shifted back to being centeredabout the first center frequency f_(C1), which was originally used fortransmitting the main and diversity receive signals from the remotedevice. Accordingly, the main and diversity receive signals arerecovered by the main and diversity frequency translation circuitries 44and 46 and provided to transceiver circuitry 48, wherein the receivesignals are processed in traditional fashion and forwarded to a mobileswitching center (MSC) or other device via an MSC interface 50.

For transmitted signals, the base housing electronics 18 will generate amain transmit signal (MAIN TX) using the transceiver circuitry 48 andprovide the main transmit signal to a power amplifier (PA) 52. Theamplified main transmit signal will then be transmitted to the duplexer40, which will send the amplifier main transmit signal over the feedercable 24 toward the masthead electronics 20, which will route the maintransmit signal to the main antenna 22M as described above.

The previous embodiment is configured to minimize the impact on theexisting transceiver circuitry 48 in the base housing electronics 18. Inan alternative embodiment, the translated main and diversity receivesignals may be presented directly to the transceiver circuitry 48, whichmay be modified to be able to process the signals directly, instead ofrequiring them to be translated back to being centered about theiroriginal center frequency, f_(C1). Further, the receive signals that aretranslated may be shifted up or down in frequency to varying degrees.For example, the receive signals may be shifted down to an intermediatefrequency, to a very low intermediate frequency, or to a near DCfrequency, such as that used in Zero IF architectures.

Although not shown, power may be fed from the base housing electronics18 to the masthead Electronics 20 via the antenna feeder. Power would becoupled to the feeder cable 24 and off of the feeder cable 24 using aconventional Bias-T as is typically done for masthead electronics 20.Furthermore, a communication link between the base housing electronics18 and masthead electronics 20 may also be desirable and implemented.The communication link could be implemented at baseband or at an RFfrequency other than those frequencies of interest to the wirelessoperator, using a low power RF transceiver.

Furthermore, if it is desirable to control the frequency translation toa high level of precision, a local oscillator (LO) signal in the form ofa sine wave could be fed up the feeder cable 24 from the base housingelectronics 18 and be extracted by the masthead electronics 20. The LOsignal could be a sine wave in the range of 100 to 200 MHz to facilitateseparation from the RX and TX signals.

Redundancy is often an issue for the masthead electronics 20. It istherefore desirable that a minimum amount of functionality be maintainedin the event of a hardware failure with either the LNAs or frequencytranslation circuitry. It would therefore be advantageous in both themain and diversity receive paths be equipped with frequency translationcircuitry. If one frequency translation circuit 32 should fail, the mainsignal would pass through the redundant circuitry unshifted and remainat its original frequency. In such an event the main receive signalcould propagate downwards to the base housing electronics 18 at itsoriginal RF frequency and the diversity receive signal would continue tobe propagated as described.

Turning now to FIG. 4, a second embodiment of the present invention isillustrated. In this embodiment, the main receive signal is nottranslated, while the diversity receive signal is translated. Thus, themain receive signal and a translated diversity receive signal arecombined in the masthead electronics 20 and sent over the feeder cable24 to the base housing electronics 18. In particular, the main receivesignal is received at main antenna 22M, and forwarded to combiningcircuitry 40 via the duplexer 28, and through an LNA 30. The diversityreceive signal is received at diversity antenna 22D, filtered by thefilter 34, amplified by the LNA 36, and translated from the first centerfrequency f_(C1) to a second center frequency f_(C2) by the diversityfrequency translation circuitry 38. The main receive signal and thetranslated diversity receive signal are combined by combining circuitry40 and sent to duplexer 26 for delivery to the base housing electronics18 over the feeder cable 24. Upon receipt, the duplexer 40 at the basehousing electronics 18 will send a composite receive signal to theseparation circuitry 42, which will provide the main receive signal tothe transceiver circuitry 48, and the translated diversity receivesignal to the diversity frequency translation circuitry 46, which willtranslate the translated diversity receive signal back to being centeredabout center frequency f_(C1) to effectively recover the diversityreceive signal, which is then provided to the transceiver circuitry 48for processing. The main transmit signal is transmitted from the mainantenna 22M as described in association with FIG. 2.

With reference to FIG. 5, a graphical illustration of the translation ofthe diversity receive signal is shown, as processed in the embodiment ofFIG. 4. As illustrated, the translated diversity receive signal isshifted to be centered about center frequency f_(C2), wherein both themain and the original diversity receive signals are centered aboutcenter frequency f_(C1).

If a masthead LNA is not desired or needed for the main receive signal,the invention can be further simplified by removing the LNA 30 andDuplexer 28 and combining circuitry 40. In such a case, both thetransmit and main receive signals can be fed directly to the duplexer26, where they will be combined with a translated diversity receivesignal. The duplexer 26 would be designed such that the main filterencompass both the main transmit and main receive frequencies, and theother filter would encompass a shifted diversity receive frequency. Thisimplementation would provide a simpler and less costly module whileminimizing transmit path loss.

The advantages of this embodiment are twofold. Firstly, the main receivepath can be composed of only passive components, thereby improvingreliability. Alternatively, if an LNA 30 is desired at the masthead 16for both the main and diversity receive signals, this embodiment remainssimpler since only the diversity receive frequency needs to betranslated at the mast, simplifying the electronics and frequency plan.

Turning now to FIG. 6, a multi-band implementation of the presentinvention is illustrated. A multi-band communication environment is onein which the same or different cellular communication techniques aresupported by a base station environment 10. As illustrated, a singlebase housing 12 is used, but different base housings 12 may be used forthe different frequency bands. In many instances, the different modes ofcommunication, whether incorporating the same or different underlyingcommunication technologies, are centered about different centerfrequencies. Two common frequencies about which cellular communicationsare centered are 800 MHz and 1900 MHz. Accordingly, the base stationenvironment 10 must be able to transmit and receive signals at both 800MHz and 1900 MHz, and may require diversity antennas 22D to assist inreceiving signals. In operation, received signals in the 800 or 1900 MHzbands (BAND 1 and BAND 2, respectively) may be received at diversityantenna 22D, wherein a duplexer 54 will send 800 MHz receive signals(800 RXD) through LNA 56 to BAND 1 frequency translation circuitry 58,which will translate the 800 MHz receive signal about a different centerfrequency. In this example, assume the BAND 1 frequency translationcircuitry downconverts the 800 MHz receive signal to a firstintermediate frequency (IF₁), wherein the downconverted signal isgenerally referred to as 800 RXD @ IF₁. Similarly, 1900 MHz receivesignals (1900 RXD) will be provided through LNA 60 to BAND 2 frequencytranslation circuitry 62, which will downconvert the 1900 MHz receivesignal to a second intermediate frequency (IF₂), wherein thedownconverted signal is represented as 1900 RXD @ IF₂.

The 800 RXD @ IF₁ and 1900 RXD @ IF₂ signals are combined usingcombining circuitry 64 to form a composite signal IF₁+IF₂, which isprovided to combining circuitry 26′, which will combine the compositesignal IF₁+IF₂ with any signals received at the main antenna 22M, and inparticular, 800 MHz and 1900 MHz receive signals (800 RX and 1900 RX).Thus, the combining circuitry 26′ may combine the 800 and 1900 MHzreceive signals with the composite IF₁+IF₂ signal and present them overthe feeder cable 24 to separation circuitry 42 provided in the basehousing electronics 18. The separation circuitry 42 will provide the 800and 1900 MHz signals to the transceiver circuitry 48, as well as sendthe 800 RXD @ IF and 1900 RXD @ IF₂ (translated) signals to respectiveBAND 1 and BAND 2 frequency translation circuitry 66 and 68. The BAND 1frequency translation circuitry 66 may upconvert the 800 RXD @ IF signalto recover the original 800 RXD signal, and the BAND 2 frequencytranslation circuitry 68 will process the 1900 RXD @ IF signal torecover the original 1900 RXD signal. The 800 RXD and 1900 RXD signalsare then provided to the transceiver circuitry 48 for processing intraditional fashion. As noted for the previous embodiment, thetransceiver circuitry 48 may be modified to process the downconverted orotherwise translated signals without requiring retranslations back tothe original center frequencies, as provided by the BAND 1 and BAND 2frequency translation circuitry 66 and 68.

Accordingly, the present invention provides for translating signals fromone or more antennas 22 in a base station environment 10 in a mannerallowing the translated signals to be combined with one another andother untranslated signals for transmission over a common antenna feeder24. The present invention is applicable to single and multi-bandcommunication environments, and is not limited to communicationtechnologies or particular operating frequencies. In general, thetranslation of received signals need only operate such that when thesignals are combined with other signals, there is no interference or theinterference is otherwise minimal or manageable. Further, the receivesignals may be from any spatially diverse array of antennas for one ormore sectors.

As noted, two base housings 12 that operate in different bands may sharethe same feeder cables 24 and masthead 16.

Redundancy is a key issue for masthead electronics 20. Active componentswhich are used in the LNA 30 and frequency translation circuitry 32, 38are less reliable than passive components used to implement theduplexers 26, combining circuitry 40, and filters 34. As such, it may benecessary to bypass the LNAs 30 within the module. An LNA bypass isstandard practice for masthead LNAs 30.

More important is redundancy in the frequency translation circuitry 32,38. Since the objective is to transmit two receive signals, main anddiversity, down the same antenna feeder 24 to the base housingelectronics 18, loss of the frequency translation function means thatonly one of the receive signals can be relayed to the base housingelectronics 18. It is therefore important to consider redundancy schemesin practice.

One approach is to simply include multiple levels of redundancy withineach circuit block. A more sophisticated scheme would be to further usefrequency translation circuitry on both the main receive and diversityreceive signals as shown in FIG. 2. However, the frequency translationcircuitry 32, 38 should be designed as to allow a signal to pass throughwith relatively little attenuation in the event of a hardware failure.Such would be the case with a serrodyne implemented using exclusivelyshunt or reflection type switches. The combining circuitry 40 could bedesigned to accept a signal at the translated receive frequency ororiginal receive frequency on either port. The frequency translationcircuitry 32, 38 would only be used in one branch at any given time, andin the other branch the signal would be passed through the frequencytranslation circuitry with little or no effect. In the event that theactive frequency translation circuitry 32, 38 should fail, the unusedfrequency translation circuitry 32, 38 could be turned on to implementthe frequency translation on this branch, and the failed frequencytranslation circuitry 32, 38 would then allow the signal to pass throughuntranslated.

Finally, in cases where four-branch receive diversity is used, it isconceivable that each sector contain one transmit signal and fourreceive signals. In such a case the present invention could easily beexpanded to translate the frequency of all receive signals oralternately on the three diversity receive signals to separatefrequencies and combine them all onto one feeder cable 24 where theywould be separated by another circuit at the base station housing 12.

Those skilled in the art will recognize improvements and modificationsto the preferred embodiments of the present invention. All suchimprovements and modifications are considered within the scope of theconcepts disclosed herein and the claims that follow.

1-25. (canceled)
 26. An apparatus comprising: a first electronics unithaving an input configured to receive a composite signal transmittedfrom a second electronics unit, the composite signal comprising a firstsignal centered around a first frequency and a second signal centeredaround a second frequency, wherein the second electronics unit isconfigured to form the composite signal by: translating the first signalto be centered around the first frequency, the first signal beingreceived by the second electronics unit as being centered around thefirst frequency and through a first antenna; and combining thetranslated first signal with the second signal, the second signal beingreceived by the second electronics unit from a second antenna andcentered around the second frequency; wherein the first electronics unitis configured to retranslate the first signal to be centered around thesecond frequency subsequent to receiving the composite signal.
 27. Theapparatus as recited in claim 26, wherein the first electronics unit islocated in a base station and is configured to received the compositesignal through a cable coupled to the second electronics.
 28. Theapparatus as recited in claim 27, wherein the second electronics unit islocated on an antenna mast that includes the first and second antennas.29. The apparatus as recited in claim 28, wherein the first antenna is adiversity antenna and wherein the second antenna is a main antenna. 30.The apparatus as recited in claim 26, wherein the first electronics unitincludes a separation unit coupled to receive the composite signal andconfigured to separate the first and second signals from the compositesignal.
 31. A method comprising: receiving, at a first electronics unit,a composite signal transmitted from a second electronics unit, whereinthe composite signal comprises a first signal centered around a firstfrequency and a second signal centered around a second frequency, andwherein the second electronics unit forms the composite signal by:translating the first signal to be centered around the first frequency,the first signal being received by the second electronics unit through afirst antenna and being centered around the first frequency; andcombining the translated first signal with the second signal, the secondsignal being received by the second electronics unit from a secondantenna and centered around the second frequency; and re-translating, atthe first electronics unit, the first signal to be centered around thesecond frequency.
 32. The method as recited in claim 31, furthercomprising the first electronics unit receiving the composite signal viaa cable coupled between the first electronics unit and the secondelectronics unit.
 33. The method as recited in claim 31, furthercomprising a separation unit in the first electronics unit separatingthe first and second signals from the composite signal, wherein saidre-translating is performed subsequent to said separating.
 34. Themethod as recited in claim 33 further comprising forwarding the firstand second signals to transceiver circuitry subsequent to saidre-translating.
 35. The method as recited in claim 34 furthercomprising: transmitting the first and second signals from thetransceiver circuitry to a mobile switching center interface; andtransmitting the first and second signals from the mobile switchingcenter interface to a mobile switching center.
 36. An apparatuscomprising: a base electronics unit configured to receive a compositesignal from a masthead electronics unit, wherein the composite signalcomprises a first signal having a first center frequency and a secondsignal having a second frequency, and wherein the base electronics unitis configured to translate the first signal to the second centerfrequency; wherein the composite signal is formed by the mastheadelectronics unit combining the first signal with the second signal,wherein the first signal is received by the masthead electronics unitfrom a diversity antenna and having the second center frequency andwherein the second signal is received by the masthead electronics unitfrom a main antenna and having the second center frequency, wherein themasthead electronics unit is configured to translate the first signal tothe first center frequency prior to combining with the second signal.37. The apparatus as recited in claim 36, wherein the base electronicsunit includes separation circuitry configured to separate the firstsignal from the composite signal and further configured to separate thesecond signal from the composite signal.
 38. The apparatus as recited inclaim 37, wherein the base electronics unit further includes translationcircuitry coupled to receive the first signal from the separationcircuitry and configured to translate the first signal from the firstfrequency to the second frequency.
 39. The apparatus as recited in claim38, wherein the base electronics unit further includes transceivercircuitry coupled to receive the first signal from the translationcircuitry and further configured to receive the second signal, whereinthe transceiver circuitry is configured to transmit the first and secondsignals to a mobile switching center interface.
 40. The apparatus asrecited in claim 36, further comprising a cable coupled to the baseelectronics unit, wherein the base electronics unit is configured toreceive the composite signal from the masthead electronics unit via thecable.
 41. An apparatus comprising: a masthead electronics unitconfigured to transmit a composite signal including first and secondsignals centered at first and second frequencies, respectively, whereinthe masthead electronics unit is further configured to: receive thefirst signal from a first antenna, wherein the first signal is centeredat the second frequency when received from the first antenna; receivethe second signal from a second antenna, wherein the second signal iscentered at the second frequency when received from the second antenna;translate the first signal to be centered around the first frequency;and combine, after translating, the first signal with the second signalto form a composite signal; wherein the masthead electronics unit isconfigured to transmit the composite signal to a base electronics unitconfigured to retranslate the first signal to be centered at the secondfrequency.
 42. The apparatus as recited in claim 41, wherein themasthead electronics unit is configured to transmit the composite signalvia a cable coupled between the masthead electronics unit and the baseelectronics unit.
 43. The apparatus as recited in claim 41, wherein thefirst antenna is a diversity antenna and the second antenna is a mainantenna.
 44. The apparatus as recited in claim 41, wherein the mastheadelectronics unit includes: a filter coupled to receive the first signalfrom the first antenna and configured to filter the first signal; a lownoise amplifier coupled to receive the first signal from the filter,wherein the low noise amplifier is configured to amplify the firstsignal; a translation unit coupled to receive the first signal from thelow noise amplifier and configured to translate the first signal to becentered at the first frequency; and a combining circuit configured tocombine the first and second signals to form the composite signal. 45.The apparatus as recited in claim 41, wherein the masthead electronicsunit is coupled to receive a transmit signal from the base electronicsunit and is further coupled to convey the transmit signal to the secondantenna for transmission.
 46. An apparatus comprising: an antennaassembly including a base electronics unit and a masthead electronicsunit, wherein the base electronics unit is configured to: receive acomposite signal from a masthead electronics unit, wherein the compositesignal comprises a first signal having a first center frequency and asecond signal having a second frequency, and wherein the baseelectronics unit is configured to translate the first signal to thesecond center frequency; and wherein the masthead electronics unit isconfigured to: receive the first signal from a first antenna, whereinthe first signal is centered at the second frequency when received fromthe first antenna; receive the second signal from a second antenna,wherein the second signal is centered at the second frequency whenreceived from the second antenna; translate the first signal to becentered around the first frequency; and combine, after translating, thefirst signal with the second signal to form a composite signal.
 47. Theapparatus as recited in claim 46, wherein the base electronics unit andthe masthead electronics unit are coupled together by a cable, whereinthe masthead electronics unit is configured to convey the compositesignal to the base electronics unit via the cable.
 48. The apparatus asrecited in claim 47, wherein the base electronics unit is configured toconvey a transmit signal to the masthead electronics unit via the cable,wherein the masthead electronics unit is configured to convey thetransmit signal to the second antenna for transmission.
 49. Theapparatus as recited in claim 46, wherein the masthead electronics unitincludes: a first translation circuit coupled to receive the firstsignal and configured to translate the first signal to being centered atthe first frequency; and a combining circuit coupled to receive thefirst signal from the translation circuit and further coupled to receivethe second signal, wherein the combining circuit is configured to formthe composite signal by combining the first and second signals.
 50. Theapparatus as recited in claim 49, wherein the base electronics unitincludes: a separation circuit coupled to receive the composite signal,wherein the separation circuit is configured to separate the first andsecond signals from the composite signal; and a second translationcircuit coupled to receive the first signal from the separation circuitand configured to re-translate the first signal to being centered at thesecond frequency.